Rosetta and Philae landing timeline

A timeline of the most crucial activities related to separation, descent and landing on 11 and 12 November.

What does Philae do during descent? Credit: ESA/ATG medialab

It has been compiled with inputs from the Flight Control Team at ESOC and the Science Operations Team at ESAC and is accurate as of now. PLEASE remember: many of these times are subject to change and confirmation, given the extremely dynamic nature of this delicate and complex operation. We’ll do our best to update this as we receive firm information, but on 12 November the live webcasts from ESA TV and ESA’s social media accounts (Twitter!) will be the best ways to get the latest information.

Admittedly, this timeline is a little dense, but we thought it better to provide more detail for those who – like us! – are extreme Rosetta & Philae fans (and you know who you are!). We’ll publish a lighter version in the main ESA website later today and there’s also a high-level version in the press kit (PDF; page 63 or in SlideShare here). And for those who wish, here is the opposite: an even more detailed version as a PDF, or also in Slideshare.

Review the notes/legend underneath for acronyms (no space mission can succeed without them!). There’s also a diagramme illustrating the delivery orbits.

All times are subject to change and should not be assumed confirmed. Actual times may vary considerably. Please follow ESA TV, the Rosetta website, the Rosetta blog and ESA social media for the latest updates. All are linked via http://rosetta.esa.int

Rosetta – Earliest start pre-delivery manoeuvre (thruster burn)Burn will be followed by loss of signal due to subsequent slew for separation
Manoeuvre expected to be about 0.46m/s & about 6 mins duration

Rosetta Lander Imaging System (ROLIS): CCD imager designed to return images of the landing site before and after Philae has landed

ADS

Active Descent System (ADS) – this system emits cold gas thrust at touchdown to avoid rebound.

BOT

Indicates when station is pointing & ready. Actual acquisition of signal may come only afterwards

DSS 25

NASA – DSN 34m Goldstone tracking station, California, USA

DSS 45

NASA – DSN 34m Canberra tracking station, Australia

DSS 55

NASA – DSN 34m Madrid tracking station, Spain

DSS 54

NASA – DSN 34m Madrid tracking station, Spain

MVR

Manoeuvre – a thruster burn to change direction and/or speed

MSS

(Mechanical Support System) is the lander side of Philae which executes the mechanical separation from the orbiter.

ESS

ESS (Electrical Support System) is the orbiter part of the lander. The ESS controls the orbiter communication interface with the lander. ESS itself operates as usual as power and data interface to the Orbiter.

You have it wrong. You’re thinking about an object with large mass/gravity to pull the lander to it. This is not the case. This isn’t a Moon/Mars landing. Think about trying to float in space, and travel at speed toward the space station. When you hit it. you will bounce off back into space. But if you have jets on your back that fire up (opposite of your travel direction) then it will push and hold you onto the surface of which you are attempting to land. If they fired down (at the surface) it would just blow you out into space.

Rockhound: Yeah, I remember this one. It’s where the, uh, the coyote sat his ass down in a slingshot then he strapped himself to an Acme rocket. Is that – is that what we’re doin’ here?
Harry Stamper: [under his breath] Rockhound.
Rockhound: No, no, really, because it didn’t work out too well for the coyote, Harry.
Harry Stamper: [talking over him] Hey, Rock. Knock it off.
Truman: Well, actually, we have a lot better rockets than the coyote.

Im sorry for the humorous comment from the movie “ARMAGEDDON ” but thats the first thing I though of when they launched this thing 10 years ago and with the confusing & seriousness of all the comments I thought it may lighten it up a bit !!

Even if this fails miserably and little Philae bounces off Agilkia and smashes Rosetta into shards it is a wonderful and magical adventure and you have already achieved so very, very much. My thanks to everyone on all the teams from NASA and ESA and everyone else.
Great work, people.

With surface temperatures so low (and, presumably, the ice so hard), what is the probability of the harpooning action either causing damage to Philae or rebounding the little fella out into space? Is there any opportunity for Philae to give it a second attempt at that point?

Who was the first scientist to suggest this as a viable mission all those years ago? How long had Comet 67P been considered as a rendezvous candidate for a mission like this?

Because of the low gravity of the comet the lander feets will “grab” the surface the same moment it tuches down and the engine on top of the lander will ignite and push the lander toward the surface. The harpoones will be fired and dig deep into the surface (from its hardness dependent). Since they are attached to the bottom of the lander with wires that will retract when the harpoons are fixed and the lander is dampend the landers mass and pressure from the engine will keep it on the surface. The wires will then retract and carefully straiten out and hold the lander via the harpoons down. The harpoons are equipped with axellerometers and pressure gauges to measure desired data to calculate the surface hardness and depth of intrution lenght.
The project originated back in the 1970ties, and target was changed when Ariane 5 rocket could not perform correctly in 2003. Postponed lauch and target from comet Wirtanen to 67P/C-G (named after two Ukrainian “scientists”. See link: http://sci.esa.int/rosetta/2279-summary/ for more details.

Try to put a 4 legged chair on an irregular surface and note that 3 legs always stay in contact. Also note that with 4 legs its quite wiggly some times shifting from one stable 3 leg geometry to an other. Lesson learned?

from the faq:
What is the gravity on 67P/Churyumov-Gerasimenko’s surface, compared with that on Earth?
Comet 67P/Churyumov-Gerasimenko is so small that its gravitational pull is several hundred thousand times weaker than on Earth. For this reason, the Rosetta lander will touch down at no more than a walking pace. It will need a harpoon to safely anchor it to the comet’s surface and prevent it from bouncing back into space.
It has a mass of ~200kg,
Churyumov-Gerasimenko 1.0×10^13kg
and about 4000m across, or 2000m to the centre of gravity.
F = GmM/r2
= ( 6.67 x 10^-11) (200kg) (10^13kg) / 2000^2
=0.3335 newtons.
…or virtually zero force.

Today is one of the greatest day in the history of space exploration.
This mission of the first attempt at a soft landing on a comet, to me is the most exciting & incredible space mission since I’ve been an amateur astronomer. (I was struggling to sleep last night due to excitement) Good to hear the separation went well.
Good Lucky to ESA for the rest of the mission.